Data pronunciation: "dayta" or "dahta"?

Wiktionary marks:

• /ˈdeɪtə/ as UK, US
• /ˈdætə/ as US
• /ˈdɑːtə/ as Australia, UK formal

Merriam-Webster lists all three pronunciations, and provides a sound file for /ˈdeɪtə/.

There's no such thing as "correct" pronunciation.

Now, to answer your question, here's what LPD3 says on this (Wells 2008):

Preference polls

BrE:

ˈdeɪtə 92%

ˈdɑːtə 6%

ˈdætə 2%

AmE:

ˈdeɪțə 64%

ˈdæțə 35%

ˈdɑːțə 1%

NB: ț stands for the (voiced) alveolar tap (flap) here. Wells uses a slightly different symbol, not the usual IPA one.

A historical perspective:

The eleventh edition of Everyman's Pronouncing Dictionary by Daniel Jones (the 1960 reprint) gives ˈdeitə as the primary variant for British English, whereas dɑːtə is given in brackets, which means, in Jones' notation, the less frequent form that is still in current use.

That depends on which country you live in and what your definition of "correct" is. The US and Australia, for example, predominantly use "dayta" but New Zealanders say "dahta".

In short, either is correct but different countries' cultures have different norms.

I vaguely remember being told that day-ta was the correct pronunciation, and that was because there was a vowel (the second 'a') following the consonant (the 't'). Now whether or not that actually applies, someone please comment because I'd love to know if I was given a load of hogwash there.

Personal experience, I find that I hear and use day-ta more than dah-ta. It is similar to the different ways that 'SQL' is pronounced among us techies - some spell it out, and some pronounce it as "sequel". Thinking about it, I find that when it is the word "data" all by itself, I use day-ta, but when it is part of another word ("database", for example) I tend to use dah-ta instead. Again, not sure if this is something that I just happened to have picked up over the years or if it is even correct. Anyone else notice the different pronunciation in situations like this?